Carbon and carbon-containing refractory materials for blast-furnaces at the Chelyabinsk Electrode Plant Joint-Stock Co.

Abstract

The effect of SiC additives and the granular composition on porosity, abrasive resistance, and endurance of carbon refractory blocks used in the blast-furnace steel-making technology. The use of microporous refractory blocks makes it possible to extend the blast-furnace production campaign by several years. The high efficiency of low heat-conducting cold-rammed mixes and a carbon-containing concentrate (available from ChEP JSC) is discussed.Since 1997, at the Chelyabinsk Electrode Plant JointStock Co. (ChEP JSC), new types of refractory carbon blocks and cold-rammed mixtures have been developed for the refractory lining of blast furnaces aimed at extending their service life.In an operating blast furnace, the carbon blocks are exposed to high thermal stress, infiltration of molten iron, structural degradation, and abrasive wear. Finally, the carbon blocks undergo cracking and develop brittleness. This results in the reduction of heat conductivity and initiates melting of the hardened layer of metal, the so-called scull, which serves as a protection for the walls and bottom of the blast-furnace hearth.All these factors adversely affect the carbon lining and lead to its degradation.To make the refractory blocks reliable in service, one will have to improve their properties such as density, heat conductivity, microporous structure, and resistance to abrasive wear.A survey of the literature has shown that effective techniques for creating a dense microporous structure of carbon blocks are:

Properties and microstructures of blast furnace carbon refractories with Al additions

“…At 1400uC, Si 2 N 2 O disappeared and more SiC formed (Figs. 8a and 9d) by reaction (10) Si 2 N 2 O(s)z5CO (g)~2SiC (s)zCO 2 (g)zN 2 (g) (10) For the 4Alz4Si sample, the Al containing compounds of Al 4 C 3 , AlN and corundum were observed at 1100uC (Figs. 8b and 11a), verifying the direct carbonisation, nitriding and oxidation reactions of Al occurred by reactions (3), ( 11) and ( 12)…”

“…8,9 Commonly, there are two routes towards increasing thermal conductivity: adding a component with high thermal conductivity and densifying the material, and also two routes towards obtaining super microporous structure: adding Si and decreasing the size of the filler grains. 10,11 One main drawback of C containing refractories is the poor oxidation resistance, and Al and Si are often used as antioxidants in such materials. Many reports can be found about the reaction mechanism and microstructure evolution of Al and Si under a reducing atmosphere.…”

Effect of Multiwalled Carbon Nanotubes on the Thermal Conductivity and Porosity Characteristics of Blast Furnace Carbon Refractories

“…The first route is adding silicon, and the second is decreasing the size of the filler grains. [6,7] In our previous work, it has been observed that the addition of appropriate silicon content along with its particle size, [8][9][10] activated alumina micropowder, [11] electric-calcined anthracite aggregates, [12] and aluminum [13] can be favorable for the formation of an excellent microporous structure. Also, two routes are proposed toward increasing TC: adding a component with high thermal conductivity and densifying the material.…”

Microstructures and Properties of Carbon Refractories for Blast Furnaces with SiO2 and Al Additions

“…[7] There are two routes toward obtaining excellent microporous structure: adding silicon and decreasing the grain size of the fillers; there are also two routes toward attaining high thermal conductivity: adding a component with high thermal conductivity and densifying the material. [9,10] In our previous work, it has been outlined that apt silicon content (8 mass pct) and its particle size (0.045 mm) can be favorable for the formation of excellent microporous structure. [11][12][13] Silica micropowders with grains of micrometer or nanometer level possess high specific surface area and activity and are widely applied in cement concrete and unshaped refractories.…”